Click to embiggen
This is Diphyllobothrium latum, a tapeworm that might make itself at home inside you if you eat undercooked fish. The picture comes from the 80s but it must’ve been pretty retro even then.
From the CDC description:
This diagram depicts the various stages in the life cycle of the tapeworm Diphyllobothrium latum, a cestode.
Diphyllobothriasis occurs in areas where lakes and rivers coexist with human consumption of raw or undercooked freshwater fish. Such areas include, but are not limited to Europe, Soviet Union, North America, Asia, Uganda and Chile.
I found the diagram in PHIL, the Public Health Image Library.